Cutting capabilities in laser machining are governed by operation conditions such as an output of a laser beam, the focusing position of the laser beam with respect to the surface of a cutting material, an assist-gas output, and the distance between the surface of the cut material and the front end of a laser-beam nozzle, and also depend on material's conditions such as a kind, a surface state, quality, composition, and the thickness of the material. Especially among those, a beam intensity distribution of the laser beam largely governs the machining capabilities; thus, it is important to effectively irradiate the beam onto the cutting material surface.
For dealing therewith, in order to effectively irradiate a beam onto a cutting material surface in a conventional laser machining nozzle, the laser beam emitted from a laser oscillator is reflected on the interior surfaces of the laser machining nozzle. Onto the interior surfaces of the laser machining nozzle, plating of a highly reflective material such as gold plating is applied. A beam intensity of the laser beam is made uniform according to this configuration, and the diameter of the intensity-uniformed laser beam thus obtained is slightly enlarged to a desired diameter to provide a laser beam configured to have a cylindrical energy distribution, by which the cutting material surface is irradiated to proceed laser cutting (for example, refer to Patent Document 1).
[Patent Document 1] Japanese Laid-Open Patent Publication No. H10-249572